This invention relates to an improved radiator construction, and in particular to an improved means of cooling the water when the engine is operating in its low idle speed condition.
In conventional radiator constructions the water tubes extend parallel between the upper and lower headers and the water drops from the upper header in parallel paths through rows of water tubes to the lower header. In these conventional radiators both the water flow and air flow through the radiator core section are quite high under a maximum power condition to provide the necessary cooling. However, when the engine is operating in a prolonged low idle condition, the water and air flow are greatly reduced, and as a consequence the heat rejection rate is not sufficient to maintain the water within the normal operating temperature range.
This invention overcomes the above-mentioned deficiency of conventional radiators when operating in the low idle speed condition by converting the water flow in the radiator core section from several parallel paths to a single series flow to thereby expose the water flowing through the radiator to a much longer cooling period. In the low idle speed condition the water flow velocities in the tubes are increased providing turbulent flow which has greater heat transfer than the laminar flow at lower velocities.
In the prior art there are many patents that disclose the use of an adjustable internal baffle for selectively restricting the flow in certain portions of the radiator, but most of these patents are concerned with preventing freezing during the warm-up period of the engine, such as disclosed by U.S. Pat. No. 1,000,259 to Hager and U.S. Pat. No. 1,330,342 to Prell. Likewise, U.S. Pat. No. 2,023,920 to Eisinger et al and Young U.S. Pat. No. 2,164,605 show the use of a temperature responsive gating means responsive to provide a bypass to prevent the cooling liquid from passing through the finned tubes until a desired high temperature is reached. Other prior art patents show the use of valving means to selectively cause the flow to either pass in parallel streams or in series through several tubes, such as disclosed in U.S. Pat. No. 2,487,484 to Simpelaar. However, none of the prior art patents disclose the concept of converting the flow of the cooled liquid from parallel paths to a series path in response to the engine speed dropping to a low idle condition.